linux-kernel - Re: [PATCH v5 1/7] mm: Refactor MM_CP_PROT

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Message-ID: <CAGsJ_4y1rJ7Omv-8ADk-cZdkAA37bxOxaeM3-vpz1MMaT_G04A@mail.gmail.com>
Date: Mon, 21 Jul 2025 07:44:39 +0800
From: Barry Song <21cnbao@...il.com>
To: Dev Jain <dev.jain@....com>
Cc: akpm@...ux-foundation.org, ryan.roberts@....com, david@...hat.com, 
	willy@...radead.org, linux-mm@...ck.org, linux-kernel@...r.kernel.org, 
	catalin.marinas@....com, will@...nel.org, Liam.Howlett@...cle.com, 
	lorenzo.stoakes@...cle.com, vbabka@...e.cz, jannh@...gle.com, 
	anshuman.khandual@....com, peterx@...hat.com, joey.gouly@....com, 
	ioworker0@...il.com, kevin.brodsky@....com, quic_zhenhuah@...cinc.com, 
	christophe.leroy@...roup.eu, yangyicong@...ilicon.com, 
	linux-arm-kernel@...ts.infradead.org, hughd@...gle.com, 
	yang@...amperecomputing.com, ziy@...dia.com
Subject: Re: [PATCH v5 1/7] mm: Refactor MM_CP_PROT_NUMA skipping case into
 new function

On Fri, Jul 18, 2025 at 5:03 PM Dev Jain <dev.jain@....com> wrote:
>
> Reduce indentation by refactoring the prot_numa case into a new function.
> No functional change intended.
>
> Signed-off-by: Dev Jain <dev.jain@....com>

Reviewed-by: Barry Song <baohua@...nel.org>

> ---
>  mm/mprotect.c | 101 +++++++++++++++++++++++++++-----------------------
>  1 file changed, 55 insertions(+), 46 deletions(-)
>
> diff --git a/mm/mprotect.c b/mm/mprotect.c
> index 88709c01177b..2a9c73bd0778 100644
> --- a/mm/mprotect.c
> +++ b/mm/mprotect.c
> @@ -83,6 +83,59 @@ bool can_change_pte_writable(struct vm_area_struct *vma, unsigned long addr,
>         return pte_dirty(pte);
>  }
>
> +static bool prot_numa_skip(struct vm_area_struct *vma, unsigned long addr,
> +                          pte_t oldpte, pte_t *pte, int target_node)
> +{

[...]

> +       /*
> +        * Skip scanning top tier node if normal numa
> +        * balancing is disabled
> +        */
> +       if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_NORMAL) && toptier)
> +               return true;
> +
> +       if (folio_use_access_time(folio))
> +               folio_xchg_access_time(folio, jiffies_to_msecs(jiffies));

Nit: I wonder if this should be moved elsewhere, since this isn't
actually about 'skipping', even though the function is named
`prot_numa_skip()`.

> +       return false;
> +}
> +

Thanks
Barry